Lag compensating device



Feb. 25, 1936. P. KOLLSMAN LAG COMPENSATING DEVICE Filed Aug. 3, 1929 Patented Feb. 1936 14 Claim.

This invention relates to lag compensating devices, and has among its objects the provision of a device of the character described, having improved counteracting means to eliminate the effect of elastic hysteresis from spring systems.

Another object of this invention is the provision of an improved device of the nature set forth which is particularly applicable to aneroid diaphragms, barometers or altimeters.

Another object of the invention is to provide improved means embodying the principle of springs subject to hysteresis effects upon deformation thereof and consisting .of materials of diiferent specific hysteresis, and the hysteresis effects of the springs being neutralized by counteracting hysteresis eifects of the same magnitude of the springs, with the resultant effect that the useful motion of the springs is substantially free of hysteresis effects at least for a short or initial time period as upon occurrence of the deformations of the springs.

A further object of the invention is to provide an improved device of the type mentioned which is of simplified and inexpensive construction, simple and reliable in operation, and efflcient in use to a high degree.

Other objects and advantages of the invent1on will become apparent as the specification proceeds.

With the aforesaid objects in view, the invention consists in the novel combinations and arrangements of parts hereinafter described in their preferred embodiments, pointed out in the subjoined claims, and illustrated on the annexed dra'wing, wherein like parts are designated by the same reference characters throughout the several views.

In the drawing:

Figure 1 is a view in side elevation of a device embodying the invention, with parts in section to show' the construction.

Fig. 2 is a plan view of the same, with parts omitted.

Figs. 3 to 5 are views in side elevation of modified forms of the invention.

Generally described, the invention provides a device for wholly or partly eliminating the effect of hysteresis in spring systems. By this invention, the compensating spring changes its shape as a result of the deformation of the main spring or aneroid, but'since the form and characteristics of the two springs are different, a change in pressure exerted on the springs will cause a major resultant movement in one direction or in the opposite direction to actuate an indicator member. When, however, the major resultant movement shall have been completed and hysteresis eflects of the two springs take place.

the eflfect of hysteresis of the compensating spring neutralizes the hysteresis effects of the main spring with the resultant effect of no actuation of the pointer. This is so because the form and characteristics of the springs are so chosen that they will have substantially the same results from hysteresis but in opposition to each other in the organizations disclosed. The invention may be practiced in various forms, but basically includes a main spring and a compensating spring. To further define the invention, if the same is embodied in an indicator, the reading thereof is preferably taken practically at the instant of a marked change in the condition shown by the indicator. The materials of the springs are chosen so that the specific elastic hysteresis or lag per unit of time of the springs may be made zero or positive or negative, consistent with the arrangements of the springs, the simplest arrangements utilizing materials of diflerent specific hysteresis, with hysteresis effect of the main spring caused by a stress applied thereto being neutralized by a counteracting hysteresis effect of substantially the same magnitude of the compensating spring, the result being that hysteresis eff cots are eliminated from the spring system either wholly or for a short period of time upon completion of the useful motion. The invention is not to be limited to any particular location of the compensating spring, as the principle herein defined includes rather the coaction of the springs as broadly defined, and, furthermore, it is applicable to any kind of pressure responsive box. While the material of the compensating spring may have a greater or lesser specific hysteresis or lag per unit of time than that of the main spring, and the latter a movement over a different range than the compensating spring, yet the invention may also be practiced by using main spring portions and an intermediate compensating spring moving as a unit, provided that the lag per unit of time of the compensating 45 spring is approximately equal to the sum of the lags per unit of time of the main spring portions, with the lags opposed to equal zero.

The advantages of the invention as here outlined are best realized when all of its features 50 and instrumentalities are combined in one and the same structure, but, useful devices may be produced embodying less than the whole.

It will be obvious to those skilled in the art to which this invention appertains, that the same 55 be incorporated in several different wastructions. The accompanying drawing, therefore, is submitted merely as showing the pre-' hysteresis i or lag per unit of time. To define the invention,

the side It may be called the main spring.

Coacting with the main spring, which may be made of phosphor bronze is a compensating spring I! which is made of a material such as zinc of high specific hysteresis. The said compensating spring is curved oppositely to the main spring and is connected to the main spring at oints It within the boundary of the latter. The connections at It may be of any suitable type whether rigid or pivotal. The compensating spring may be of elongated, or other form. When considered with reference to the longitudinal direction of the compensating spring, the main spring may be said to have ends at l1. Connected to the compensating spring is a link It which operates a pointer It, the position of which can be read on a scale 20.

In operation, it is seen that when the diaphragm responds to a decrease of pressure, the main spring tends to move into a plane, and hence to straighten the compensating spring It. Since the main spring is longer than the com- 'pensating spring, the movement of the main device may be wholly or substantially neutralized, for the few initial seconds during which lag occurs. Thereafter the time element of hysteresis may affect the pointer reading, but the object of this invention is to permit accurate and practically immediate reading of an instrument. After sufilcient time has elapsed for all lag to disappeanthe instrument will again read accurately.

In Fig. 3 is shown a modification of the invention in which the aneroidcapsule 2| is of a slightly diiferent form, and the compensating spring I! is rigidly connected toa side wall of the same by means of arms 22, thus spacing the compensating spring from the main spring. Relative adiustability may be provided between the main spring and the compensating spring, for example, by changing the curvature or length of the latter. This may be accomplished in various ways as, for instance, by securing the compensating spring to the arms '22 with screws 22a that pass through slots lid in the compensating spring, the screws being threaded into the said arms. To adJust the compensating spring it is merely necessary to loosen the screws and deflect the spring into the desired shape after which the screws are tightened. In all other respects, this modification functions like the device l0.

mmimmmmmam invention, wherein the aneroid 22 has centrally connectedtooneorbothoppositewallsthere of at 24 any suitable leaf spring 2|, or the like, of a material of low specific hysteresis, which'may be in the nature of' a loop, the-long sides of whichmay extend approximately at right-angles to theaxis of the aneroid The compensating spring ll consistingofmaterialofhighspecific hysteresismaybe-connectedtothesprhrgfl at any suitable points therealons. as, for instance at 2|. It'is noted that in this arrangement, the compensating'spring coacts indirectly with the aneroid main spring, an intermediate member or spring being provided. Accordingly, the compensating spring may have a large range of. variation in its length relation to the main spring; it may be considerably longer with respect to the diameter of the aneroid, permitting any corresponding change in itshysteresis efiect, so long as the motions of the main and compensating springs neutralize according to the mode of operation hereinbefore described. Among the advantages of-this form of the invention may be mentioned that the aneroid may act at a single point 24; furthermore, the entire spring area of the aneroid is efiective for useful motion. InFig.5isshownafurthermodificationof the invention in which a compensating spring 21 coacts with an aneroid or spring 22 at a single point without the use of an intermediate spring. The spring 21 may be of any suitable form, for instance, in the nature of a tension coil spring. One end of the spring 21 is connected to the aneroid at as, and its other end 22 is connected to any co-operating spring such as a leaf spring 2| at an end of the same, the other end being secured to a support 32. Since the compensating spring is under tension, the spring II is constantly under a certain stress. The compensating spring may consist of a material having a high specific hysteresis, and the spring 2| may consist of material of a low specific hysteresis. Since springs 22 and II have similar specific hysteresis, they may be considered as parts of a main spring means, and particularly so where, asinthiscase,bothofthesespringshavestationary mountings and are thus permanently interrelated as a unit. In operation, when the atmospheric pressure on the aneroid capsule is relieved, the same expands, and may therefore be considered as moving upward. Hence the tension on the springs 21 and It is correspondingly relieved, so that the spring 3| is caused to move upward. The spring 21 likewise is caused to move upward but contracts slightly due to the diminished tension. At or soon after the instant that this motion is completed, as for a rapid and marked change of the atmospheric pressure, the specific hysteresis or lag per unit of the materials of the different springs occurs, with resultant counteracting hysteresis effects of substantially equal, magnitude of the springs. Thus the motion of the aneroid capsule now continues as before, further relieving the stresses on the springs 3| and 21, the spring 2| tending to move to the same degree as the aneroid capsule, because the specific hystween the springs 28 and 3 I and since the spring ii is naturally weaker than the spring 28, the spring 3| is deflected downward against its lagging tendency and to a degree directly determined by whatever might be the specific hysteresis of the material of the spring 21, Hence the hysteresis effects counteract each other and the total lag of the system is diminished. If it be desired not merely to decrease the lag of the spring system, but to reduce it substantially to a zero, thenthe lag per unit of time of the material of the spring 21 must equal substantially the sum of that of the springs 28 and 3 I; In other words, assume that the lag per unit of time were equal for the materials of the three springs, the lags for the springs 21 and 3| would merely counterbalance each other, so that the lagging motion of the spring 28 would not beafiected. But if the lag per unit of time of the material of spring 21 is equal to the sum of those for the springs 28 and 3i, then the hysteresis effect, or at least the total lag per unit of time for the system may be made approximately zero. In actual practise the closeness with which the result is attained, depends merely upon the degree of care employed by the trial and error method in designing the system, scraping down one or more of the springs, and the like. It will ordinarily sumce to slightly change the size or shape of either of the springs 21 or 3| until, by proper calibration, it is seen that the instrument reads accurately at the time or instant after occurrence of a sudden rapid change in the stress of the system. Hence it may be said that by this invention the instantaneous effect of hysteresis is eliminated, substantially instantaneously compensated .for, or neutralized, and an accurate instantaneous reading obtained. In each case herein the compensating spring, such as I5 andZ'l may be made of zinc, and the main spring ormain spring assembly such at 23 and 25, and 28 and 3| of phosphor bronze.

I claim:

1. A device including a main plate spring, and a compensating plate spring smaller than the main spring,'said springs being curved in opposite directions, the compensating spring being connected at its ends to the main spring to move with the deformation of the main spring and to be caused to deform as a result of such deformation of the main spring, the deformation of the compensating spring being thus smaller than that of the main spring, and the hysteresis effects of the compensating. spring being equal to and counteracting the hysteresis effects of the main spring for eliminating the substantially instantaneous effect of hysteresis from the device.

2. A device including a pressure responsive diaphragm, a curved main plate spring centrally connected to the diaphragm, the end portions of said spring being relatively fixed, a compensating spring curved in opposite relation of the main spring, said compensating spring being shorter than the main spring and consisting of a material having a higher specific hysteresis than the material of the main spring, said compensating spring being connected to the main spring to be deformed by the latter as a result of the deformation of. the main spring by the diaphragm, and an indicator coacting with the compensating spring, the pressure responsive diaphragm being subject, upon changes of stress applied to the same, to a hysteresis efiect neutralized by a counteracting hysteresis effect of substantially the same magnitude of the springs whereby the springscompensate for the specific hysteresis of the diaphragm to produce an accurate instantaneous indication by said indicating means of the action of said diaphram.

3. A device having an indicator and springs of different form and characteristics including a main spring means, and a compensating spring means, said spring means being interconnected so that the force of the compensating spring means is adapted to act counter to that of the main spring means, with a deformation in the main spring means directly causing a deformation in the compensating spring means, said spring means being so different from each other that achange in pressure exerted on both spring means will cause a major resultant movement in one direction or in an opposite direction to actuate the indicator, -and the material of the different spring means each having a specific hysteresis different than that of the other, and the spring means being so related to each other that the hysteresis effect of the compensatingv spring means is in opposition to and neutralizes that of the main spring means with the resultant effect of no actuation of the indicator from hysteresis effects.

4. In an indicator device, a spring system comprising a single resilient main spring sensitive to gaseous pressure, and a compensating spring, said main and compensating springs being interconnected so that a deformation of the main spring causes an opposing deformation of the "compensating spring, said springs being so different from each other that a change in pressure exertedon the main spring will cause a major resultant movement in one or in an opposite direction of the spring system to actuate an indicator, and the different springs each having a specific hysteresis different than that of the other, and the springs being so related to each other than the hysteresis eifects of the compensating spring act in opposition to and neutralize those of the main spring.

5. A device including a pressure responsive diaphragm of a material having a low specific hysteresis, a compensating spring of a material of high specific hysteresis connected thereto, and a fixed spring of a material of low specific hysteresis connected to the compensating spring independentlyof the diaphragm to continuously exert'a stress thereon, so that the hysteresis effect of the pressure responsive diaphragm and fixed spring, caused by a change in stress applied to the sama is neutralized by a counteracting hysteresis effect of the same magnitude of the compensating spring, and an indicator coacting with the springs and diaphragm to indicate the performance of the latter without the initial efiect of lag.

6. A device including a spring system instantaneously compensated for hysteresis, said system having a main spring subject to hysteresis effect upon changes of stress applied thereto, a compensating spring of a material having a different specific hysteresis than the material of the main spring and being so arranged relative thereto as to counteract the specific hysteresis of the main spring, and resilient means of a material having a specific hysteresis similar to that of the main spring, said resilient means being connected to one of the springs and causing a stress to be exerted to deform the compensating spring, the said hysteresis effect of the main spring and resilient means being neutralized by an equal counteracting hysteresis effect of the compensat- 8 sp 7. A spring system substantially instantaneously compensated for hysteresis, including a stress receiving main spring subiect to hysteresis effect upon changes of stress applied thereto, means connected thereto for counteracting the hysteresis eflect of the main spring, said means including a compensating spring of a material having a diilerent specific hysteresis than that of the main spring, and a resilient member of a material having a specific hysteresis similar to that of the main spring, said member being connected to the compensating spring and said means being so arranged relative to the-main spring as to be movable in the same general direction therewith with the resilient member maintaining a stress on the compensating spring, with the said hysteresis efiect-of the main spring and resilient member being neutralized by an equal counteracting hysteresis efiect of said means.

8. A spring system substantially instantaneously compensated for hysteresis including a main spring subject to hysteresis efiect upon changes of stress applied thereto, a compensating spring connected at one end thereto, and a third spring connected to the opposite end of the compensating spring for continually exerting a stress thereon, the main and third springs consisting of material having a specific hysteresis of similar degree, the compensating spring consisting of a material having a different specific hysteresis than said main and third springs, and the hysteresis effect of the main spring and third spring being neutralized by a substantially equal counteracting hysteresis eifect of the compensating spring.

9. A spring system substantially instantaneously compensated for hysteresis including a main spring subject to hysteresis efiect upon changes of stress appliedthereto, a bowed compensating spring of a material having a different specific hysteresis than that of the main spring, and an intermediate oppositely bowed spring of a material having a specific hysteresis similar to that of the main spring, the intermediate spring being connected to the ends of the compensating spring'and to the main spring in spaced relation to said ends so that the-intermediate spring under actuation of the main spring changes the curvature of the compensating spring, and the compensatlng spring being arranged to deform in a difierent direction than the main spring, with the hysteresis efl'ect of the main spring being neutralized by a counteracting substantially equal hysteresis effect, of the compensating spring.

10. A spring system substantially instantaneously compensated for hysteresis including an expansible diaphragm subject to hysteresis effect upon changes in stress applied thereto, a leaf spring connected at a point to said diaphragm, and a bowed compensating spring connected at its ends to the leaf spring, the latter being of a material having a specific hysteresis similar to that of the material of the main spring, the compensating spring being of a material having a different specific hysteresis than that of the main spring, the compensating spring being deformed by deformation of the leaf spring under actuation of the main spring with the deformation of the compensating spring occurring in opposite .direction relative to that of the main spring, and the hysteresis efi'ect of the diaphragm being neutralized by a substantially equal counteracting hysteresis effect of the other springs.

11. A device including a pressure responsive spring diaphragm, and a compensating spring of a material having a different specific hysteresis than that of said diaphragm and being adapted to deflect in a different direction in a diilerent degree than said diaphragm, the compensating spring being connected at its ends to the diaphragm so that a deflection oi the diaphragm causes a deflection of the compensating spring in approximately inverse proportion to the specific hysteresis of the different springs, and the hysteresis effect of the diaphragm being neutralized by an equal counteracting hysteresis tralized by a counteracting substantially equal hysteresis effect of the compensating spring.

13. A spring system having useful motion of the type disclosed, comprising a main spring means,'an elongated compensating spring, the

- ends of the compensating spring being connected to the main spring means so that the latter acts on the compensating spring in opposed relation and subjects the same to the deformations of the main spring means, and the eflects of the hysteresis of the compensating spring upon deformation being substantially equal and opposite to the eflects of hysteresis of the main spring means, whereby the spring system is substantially instantaneously compensated for hysteresis.

14. A device having a spring system substantially instantaneously compensated for hysteresis, including a main spring means subject to hysteresis effect upon changes of stress applied thereto, a compensating spring of a material having a relatively high specific hysteresis, the main spring means having portions of a material having a relatively low specific hysteresis, the compensating spring having its ends connected to the main spring portions so as to be stressed thereby and to be responsive to deformations of the main spring portions, and the compensating spring having a lesser range of motion than the main spring means, with the hysteresis effect of the main spring means being neutralized by a substantially equal and counteracting hysteresis effect of the compensating spring.

PAUL xoussum. 

